Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS INCLUDING CONVERTING RESISTIVE POWDER TO FUSED HEATER
ELEMENT USING LASER METAL DEPOSITION APPARATUS
TECHNICAL FIELD
An aspect of the present invention generally relates to (but is not limited
to) a process,
including (but not limited to): converting a resistive powder to a fused
heater element by
using a laser metal deposition apparatus.
BACKGROUND
io The first man-made plastic was invented in Britain in 1851 by Alexander
PARKES. He
publicly demonstrated it at the 1862 International Exhibition in London,
calling the material
Parkesine. Derived from cellulose, Parkesine could be heated, molded, and
retain its shape
when cooled. It was, however, expensive to produce, prone to cracking, and
highly
flammable. In 1868, American inventor John Wesley HYATT developed a plastic
material
he named Celluloid, improving on PARKES' invention so that it could be
processed into
finished form. HYATT patented the first injection molding machine in 1872. It
worked like a
large hypodermic needle, using a plunger to inject plastic through a heated
cylinder into a
mold. The industry expanded rapidly in the 1940s because World War II created
a huge
demand for inexpensive, mass-produced products. In 1946, American inventor
James
Watson HENDRY built the first screw injection machine. This machine also
allowed material
to be mixed before injection, so that colored or recycled plastic could be
added to virgin
material and mixed thoroughly before being injected. In the 1970s, HENDRY went
on to
develop the first gas-assisted injection molding process.
Injection molding machines consist of a material hopper, an injection ram or
screw-type
plunger, and a heating unit. They are also known as presses, they hold the
molds in which
the components are shaped. Presses are rated by tonnage, which expresses the
amount of
clamping force that the machine can exert. This force keeps the mold closed
during the
injection process. Tonnage can vary from less than five tons to 6000 tons,
with the higher
figures used in comparatively few manufacturing operations. The total clamp
force needed
is determined by the projected area of the part being molded. This projected
area is
multiplied by a clamp force of from two to eight tons for each square inch of
the projected
areas. As a rule of thumb, four or five tons per square inch can be used for
most products.
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If the plastic material is very stiff, it will require more injection pressure
to fill the mold, thus
more clamp tonnage to hold the mold closed. The required force can also be
determined by
the material used and the size of the part, larger parts require higher
clamping force. With
Injection Molding, granular plastic is fed by gravity from a hopper into a
heated barrel. As
the granules are slowly moved forward by a screw-type plunger, the plastic is
forced into a
heated chamber, where it is melted. As the plunger advances, the melted
plastic is forced
through a nozzle that rests against the mold, allowing it to enter the mold
cavity through a
gate and runner system. The mold remains cold so the plastic solidifies almost
as soon as
the mold is filled. Mold assembly or die are terms used to describe the
tooling used to
io produce plastic parts in molding. The mold assembly is used in mass
production where
thousands of parts are produced. Molds are typically constructed from hardened
steel, etc.
Hot-runner systems are used in molding systems, along with mold assemblies,
for the
manufacture of plastic articles. Usually, hot-runners systems and mold
assemblies are
treated as tools that may be sold and supplied separately from molding
systems.
US Patent Number 4897150 discloses direct write techniques wherein, for
example, an
electron beam "writes" a pattern in photoresist on an integrated circuit or
other semi-
conductive element. Some of these prior direct write techniques have also
included the use
of laser beams. Such laser assisted deposition techniques involve the
deposition of metal
from an organometallic gas or polysilicon from silane (SiH4).
US Patent Number 7001467 discloses a device and method for depositing a
material of
interest on a receiving substrate includes a first laser and a second laser, a
receiving
substrate, and a target substrate. The target substrate comprises a laser
transparent
support having a back surface and a front surface. The front surface has a
coating that
comprises the source material, which is a material that can be transformed
into the material
of interest. The first laser can be positioned in relation to the target
substrate so that a laser
beam is directed through the back surface of the target substrate and through
the laser-
transparent support to strike the coating at a defined location with
sufficient energy to
3o remove and lift the source material from the surface of the support. The
receiving substrate
can be positioned in a spaced relation to the target substrate so that the
source material is
deposited at a defined location on the receiving substrate. The second laser
is then
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positioned to strike the deposited source material to transform the source
material into the
material of interest.
A conducting silver line was fabricated by using a UV laser beam to first
transfer the coating
from a target substrate to a receiving substrate and then post-processing the
transferred
material with a second I R laser beam. The target substrate consisted of a UV
grade fused
silica disk on which one side was coated with a layer of the material to be
transferred. This
layer consisted of Ag powder (particle size of a few microns) and a
metalloorganic
precursor which decomposes into a conducting specie(s) at low temperatures
(less than
l0 2000 C.). The receiving substrate was a microwave-quality circuit board
which has various
gold electrode pads that are a few microns thick. A spacer of 25-micron
thickness was used
to separate the target and receiving substrates.
Silver was first transferred with a focused UV (A=248 nm or A=355) laser beam
through the
is target substrate at a focal fluence of 225 mJ/cm2. The spot size at the
focus was 40 pm in
diameter. A line of "dots" was fabricated between two gold contact pads by
translating both
the target and receiving substrates together to expose a fresh area of the
target substrate
for each laser shot while the laser beam remained stationary. The distance
between the
laser spots was approx. one spot diameter. A pass consisted of approximately
25 dots and
20 a total of 10 passes (superimposed on one another) was made. The target
substrate was
moved between each pass. After the transfers, the resistance between the gold
pads as
measured with an ohmmeter was infinite (>20-30 Megaohms).
US Patent Number 7014885 discloses device and method that is useful for
creating a
25 deposit of electrically conducting material by depositing a precursor
material or a mixture of
a precursor material and an inorganic powder that is transformed into an
electrical
conductor. For creating deposits of metals, such as for conductor lines, any
precursors
commonly used in chemical vapor deposition (CVD) and laser-induced chemical
vapor
deposition (LCVD) may be used. Examples include, but are not limited to, metal
alkoxides,
30 metal diketonates and metal carboxalates.
US Patent Number 5132248 discloses a process for deposition of material on a
substrate,
for example, the deposition of metals or dielectrics on a semiconductor laser,
the material is
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deposited by providing a colloidal suspension of the material and directly
writing the
suspension on the substrate surface by ink jet printing techniques. This
procedure
minimizes the handling requirements of the substrate during the deposition
process and
also minimizes the exchange of energy between the material to be deposited and
the
substrate at the interface. The deposited material is then resolved into a
desired pattern,
preferably by subjecting the deposit to a laser annealing step. The laser
annealing step
provides high resolution of the resultant pattern while minimizing the overall
thermal load of
the substrate and permitting precise control of interface chemistry and inter-
diffusion
between the substrate and the deposit.
SUMMARY
The inventors have researched a problem associated with known molding systems
that
inadvertently manufacture bad-quality molded articles or parts. After much
study, the
inventors believe they have arrived at an understanding of the problem and its
solution,
is which are stated below, and the inventors believe this understanding is not
known to the
public.
Current heater construction typically involves packaging of a nichrome wire
element (nickel-
chromium resistance wire) in various forms. More advanced methods may use
screen
printed techniques requiring high firing temperatures and/or customized
screens for each
configuration. Other known methods may rely on thermal spray application of a
layer and
selectively removing portions of the layer to produce the desired heating
element. For
example, additional known methods may relay on thermal spray techniques in
which a
specialized mask is used to create the desired heater configuration and
pattern. Still other
known methods may utilize inkjet style print heads with the resistive medium
suspended in
a solvent or other liquid to directly write a patterned heater onto a
substrate.
According to one aspect, there is provided a process (200), comprising: a
transfer operation
(204), including transferring a resistive powder (106) to an electrically
insulated element
(102); and a converting operating (206), including converting at least some of
the resistive
powder (106) to a fused heater element (108) by using a laser metal deposition
apparatus
(110), the fused heater element (108) being fused to the electrically
insulated element
(102).
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Other aspects and features of the non-limiting embodiments will now become
apparent to
those skilled in the art upon review of the following detailed description of
the non-limiting
embodiments with the accompanying drawings.
DETAILED DESCRIPTION OF THE DRAWINGS
The non-limiting embodiments will be more fully appreciated by reference to
the following
detailed description of the non-limiting embodiments when taken in conjunction
with the
1o accompanying drawings, in which:
FIG. 1 depicts a schematic representation of a laser metal deposition
apparatus (110);
FIG. 2 depicts another schematic representation of the laser metal deposition
apparatus
(110) of FIG. 1; and
FIG. 3 depicts a schematic representation of a process (200) for using the
laser metal
deposition apparatus (110) of FIG. 1 or FIG. 2.
The drawings are not necessarily to scale and may be illustrated by phantom
lines,
diagrammatic representations and fragmentary views. In certain instances,
details not
necessary for an understanding of the embodiments (and/or details that render
other details
difficult to perceive) may have been omitted.
DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENT(S)
FIG. 1 depicts the schematic representation of the laser metal deposition
apparatus (110).
Mold-tool systems, hot-runner systems and molding systems may include, at
least in part,
components that are known to persons skilled in the art, and these known
components will
3o not be described here; these known components may be described, at least in
part, in the
following reference books (by way of example): (i) "Injection Molding
Handbook' authored
by OSSWALD/TURNG/GRAMANN (ISBN: 3-446-21669-2), (ii) "Injection Molding
Handbook' authored by ROSATO AND ROSATO (ISBN: 0-412-99381-3), (iii)
"Injection
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Molding Systems" 3rd Edition authored by JOHANNABER (ISBN 3-446-17733-7)
and/or (iv)
"Runner and Gating Design Handbook' authored by BEAUMONT (ISBN 1-446-22672-9).
It
will be appreciated that for the purposes of this document, the phrase
"includes (but is not
limited to)" is equivalent to the word "comprising". The word "comprising" is
a transitional
phrase or word that links the preamble of a patent claim to the specific
elements set forth in
the claim which define what the invention itself actually is. The transitional
phrase acts as a
limitation on the claim, indicating whether a similar device, method, or
composition infringes
the patent if the accused device (etc) contains more or fewer elements than
the claim in the
patent. The word "comprising" is to be treated as an open transition, which is
the broadest
io form of transition, as it does not limit the preamble to whatever elements
are identified in
the claim.
An electrically insulated element (102) is placed on a substrate (104). A
resistive powder
(106) is placed on the electrically insulated element (102). At least some of
the resistive
is powder (106) is converted to a fused heater element (108) by using a laser
metal
deposition apparatus (110). The fused heater element (108) becomes fused to
the
electrically insulated element (102). The electrically insulated element (102)
may include a
layer of insulation material. The substrate (104) may include, for example, a
layer of
substrate material.
Examples of the electrically insulated element (102) may include: aluminum
nitride,
aluminum oxide, magnesium oxide, zirconia, mica, diamond, etc. Example of the
substrate
(104) may include: carbon steel, tool steel, stainless steel, copper and
copper based alloys,
aluminum, titanium, aluminum nitride, aluminum oxide, silicon carbide, or
other metallic or
ceramic materials. Example of the resistive powder (106) may include: nickel-
chromium
(also known as ni-chrome), conductive ceramics, tungsten, etc.
According to a first variation, the placing of the resistive powder (106) on
the electrically
insulated element (102) includes (but is not limited to): using a feeder
nozzle (112) to spray
the resistive powder (106) on the electrically insulated element (102).
FIG. 2 depicts another schematic representation of the laser metal deposition
apparatus
(110) of FIG. 1. According to a second variation, the placing of the resistive
powder (106)
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on the electrically insulated element (102) includes (but is not limited to):
depositing the
resistive powder (106) as a layer on the electrically insulated element (102).
FIG. 3 depicts a schematic representation of the process (200) for using the
laser metal
deposition apparatus (110) of FIG. 1 or FIG. 2. The process (200) includes
(but is not
limited to): (i) a fixing operation (202); (ii) a transfer operation (204);
and (iii) a converting
operating (206). The fixing operation (202) includes (but is not limited to):
fixing the
electrically insulated element (102) on a substrate (104). The transfer
operation (204)
includes (but is not limited to): transferring a resistive powder (106) to the
electrically
1o insulated element (102). The converting operating (206) includes (but is
not limited to):
converting at least some of the resistive powder (106) to a fused heater
element (108) by
using a laser metal deposition apparatus (110). The fused heater element (108)
then
becomes fused to the electrically insulated element (102).
It will be appreciated that the laser metal deposition apparatus (110) may be
used to create
or to form a customized heater profile (wattage and watt distribution) in a
single write step.
By directly writing the heater element, that is, using the converting
operating (206), the cost
may be reduced and the number of steps required to produce the fused heater
element
(108) are also reduced. In addition, the ability to articulate a laser head of
the laser metal
deposition apparatus (110) may allow a build up of the fused heater element
(108) on a
contoured surface, and/or a complex-shaped surface.
The laser metal deposition apparatus (110) uses a laser energy source to fuse
the resistive
powder (106) on the electrically insulated element (102), such as a ceramic
including
magnesium oxide or aluminum oxide, as well as diamond based materials. Several
method
may be used to position the resistive powder (106) on the over the
electrically insulated
element (102). The resistive powder (106) may be: (i) fed into a laser beam
using a
compressed gas (as depicted in FIG.1), or (ii) may be spread over a surface to
a prescribed
thickness and selectively fused to the substrate (104) using the laser beam
path to
3o determine the element configuration (as depicted in FIG. 2). Additional
passes of a laser
beam may be used to make thicker layers as desired for increased flexibility
in controlling
the thermal and electrical characteristics of the fused heater element (108).
A laser head
may move (or be steered via mirrors), the substrate (104) may be moved, or
even both may
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be moved to achieve a desired geometry and configuration for the fused heater
element
(108).
An aspect (or example) of the present invention provide a process for
producing a profiled
heating element in a single step on a substrate (104) using a laser metal
deposition (LMD),
in which a powder is fed into a laser beam focused on the surface of a
substrate (104). The
powder is fused to the substrate (104) by the localized laser energy in only
the regions in
which the laser beam is focused. By applying a trace of the correct material
to directly form
the heater element trace, a customized heater may be built upon the substrate
(104) (such
to as a ceramic material, an insulated substrate, etc.) in one direct writing
step with no
requirements for either masking or selective removal of the deposited
material. This
arrangement allows for the creating of a customized heater element with lower
cost and
less steps than would otherwise be the case using known methods.
It is understood that the scope of the present invention is limited to the
scope provided by
the independent claims, and it is also understood that the scope of the
present invention is
not limited to: (i) the dependent claims, (ii) the detailed description of the
non-limiting
embodiments, (iii) the summary, (iv) the abstract, and/or (v) description
provided outside of
this document (that is, outside of the instant application as filed, as
prosecuted, and/or as
granted). It is understood, for the purposes of this document, the phrase
"includes (but is
not limited to)" is equivalent to the word "comprising". The word "comprising"
is a transitional
phrase or word that links the preamble of a patent claim to the specific
elements set forth in
the claim which define what the invention itself actually is. The transitional
phrase acts as a
limitation on the claim, indicating whether a similar device, method, or
composition infringes
the patent if the accused device (etc) contains more or fewer elements than
the claim in the
patent. The word "comprising" is to be treated as an open transition, which is
the broadest
form of transition, as it does not limit the preamble to whatever elements are
identified in
the claim. It is noted that the foregoing has outlined the non-limiting
embodiments. Thus,
although the description is made for particular non-limiting embodiments, the
scope of the
present invention is suitable and applicable to other arrangements and
applications.
Modifications to the non-limiting embodiments can be effected without
departing from the
scope of the independent claims. It is understood that the non-limiting
embodiments are
merely illustrative.
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